Motor starting crank safety device



Sept. 21, 1937. A. w. HODGES I 2,093,965

MOTOR STARTING CRANK SAFETY DEVICE Filed NOV. 30, 1936 ATTOR N EYS Patented Sept. 21, I937 STAT PATENT OFFICE 2 Claims.

This invention relates to safety devices for crank handles of engines and has for the primary object the provision of a device of this character which will not interfere with normal manual cranking of an engine and which will automatically disengage the crank handle from the engine should the latter run in a reverse direction from any cause such as backfiring or preignition and thereby eliminate the danger of injury to the person cranking the engine.

With these and other objects in view, this invention consists in certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawing, in which Figure 1 is a fragmentary front elevation illustrating an engine and a crank handle therefor equipped with a safety device constructed in accordance with my invention.

Figure 2 is a front elevation, partly in section, showing the safety device.

Figure 3 is a fragmentary side elevation partly in section showing the dogs for the disengagement of the crank handle from the engine should the latter run in a reverse direction.

Figure 4 is a fragmentary sectional view illustrating one of the dogs acting to disengage the crank handle from the engine.

Figure 5 is a fragmentary sectional view illustrating a companion dog showing the latter swinging into position to permit the movement of the crank handle in the proper direction for the cranking of the engine.

Figure 6 is a fragmentary sectional view illustrating another dog of a group of dogs acting to disengage the crank handle from the engine.

Figure 7 is a View similar to Figure 6 showing a companion dog to the dog shown in Figure 6 swinging on its pivot to permit passing of the crank handle when the latter is moving in a direction to crank the engine.

Referring in detail to the drawing, the numeral l indicates a fragmentary portion of an internal combustion engine and 2 the crank shaft thereof having secured thereto a clutch element 3 to be engaged by a pin 4 of a crank handle 5. The foregoing description sets forth a conventional construction employed for the cranking of an internal combustion engine. It is a well known fact that should the engine backfire or run in a reverse direction, the person cranking the engine is liable to injury. To prevent injury to a person my invention isreadily adaptable to the engine and consists of a plate 6 arranged vertically in front of the engine and suitably secured to the latter. The plate 6 has an opening forming a journal for the crank handle 5. The crank handle 5 is free to rotate in the opening as well as to slide in said opening for the engagement and disengagement of the pin 4 with the clutch element 3.

On opposite sides of the vertical center of the plate 6 are pairs of slots 1 and 8. Located in the slots and adjacent one end of each slot is a pin 9. Journaled on the pins 9 and in the slots 7 are dogs I0 and journaled on the pins in the slots 8 are dogs H. The dogs l0 have extensions l2 on which weights I3 are formed. The weights I3 are for the purpose of causing the dogs to assume a position substantially of that shown in Figure '7. The dogs II are pivoted adjacent one end thereof so that said dogs normally assume the full line position, as shown in Figure 5. The pivoted ends of the dogs II have formed thereon stops M to limit the pivotal movement of said dogs into the slots 8. The stops permit the dogs II to move substantially within the slots and slightly beyond the dotted line position shown in Figure 5. The dogs ID and H each have a straight face A and an inclined face B. The crank handle when engaging the inclined faces B of the dogs l0 and I I cause said dogs to swing out of the path of movement of the crank handle. However, when the crank handle comes in contact With the straight faces A of said dogs an endwise movement is imparted to the crank handle for the purpose of disengaging the pin thereof from the clutch element 3 thereby freeing the crank handle from the engine.

In operation, when facing the engine I the crank handle is moved into engagement with the clutch element 3 and rotated in a clockwise direction to start the engine. However, should the engine run in a reverse direction due to backfire or preignition, the crank handle will engage a straight face of the dog adjacent thereto and be forced in an endwise direction away from the engine thereby freeing the crank handle from the engine. As long as the crank handle rotates in a clockwise direction the crank handle may pass freely by the dogs due to the crank handle coming in contact with the faces B and causing said dogs to swing out of the path of movement of the crank handle. The dogs when acting to check the movement of the crank handle in a reverse direction and to bring about disengage ment of said crank handle from the engine move into engagement with end walls of the slots and the crank handle engaging the straight walls of said dogs will prevent counterclockwise rotation of the handle and also cause an endwise movement of the handle away from the engine.

Having described the invention, I claim:

1. In combination with an engine having a clutch element on the crank shaft thereof and a crank handle provided with a pin to be brought into engagement with the clutch element for the cranking of the engine by the rotation of the handle in one direction, a fixed plate on the engine and forming a support for the crank handle with the latter free to slide towards and from the crank shaft, and pairs of dogs pivoted on said plate and adapted to pivot freely in one direction when engaged by the crank handle during rotation of the latter in a direction to crank theengine and any one thereof adapted to abut said plate when engaged by the'crank handle moving in a reverse direction caused by backfiring of the engine to bring about disengagement of the crank handle from the crank shaft.

2. In combination with an engine having a clutch element on its crank shaft and a crank handle provided with a pin to engage with the clutch element whereby the engine may be cranked by rotating the crank handle in a clockwise direction, a vertically arranged plate secured on the engine and having an opening to receive the crank handle and provided with pairs of slots arranged at opposite sides of the vertical center of said plate, pairs of dogs pivoted in said pairs of slots and each having straight and beveled faces and each free to pivot in one direction when the crank handle engages the beveled face thereof and to engage the plate when the crank handle engages the straight face thereof to bring about endwise movement of the crank handle and there- 1 by the disengagement of the latter from the 

